The Anzac spirit permeates Australian military culture but a top think tank has warned that New Zealand risks becoming a "Western ally with Chinese characteristics" because it has embraced a less strident tone towards Beijing's assertiveness.

In a report to be released on Wednesday, Australian Strategic Policy Institute senior analyst Mark Thomson is urging the government to step up its military engagement with New Zealand to shore up the alliance.

The report said that while Australia and New Zealand had a common goal in preserving regional stability, Australia spent significantly more per capita on defence because Canberra systematically accepted higher costs and risks.

Malcolm Turnbull and New Zealand counterpart Jacinda Ardern get on but a think tank has called for greater defence ties between the two countries amid China's rise. DAVID GRAY

New Zealand had accepted Australia would shoulder the burden in the local region and while Wellington had withdrawn from the ANZUS Treaty in the mid-1980s, it continued to benefit from the presence of US forces in the region.

"The antipodean pair could either draw closer together or be pulled apart, and each will continue to calibrate its strategic distance from the US," the report said.

"It's impossible to say where each will be in five or 10 years, but, as the least committed of the pair, New Zealand is at greatest risk of becoming a Western ally with Chinese characteristics."

While Australia and New Zealand have both continued to deploy troops to recent conflicts, with the notable exception being the Kiwis' absence from the 2003 invasion of Iraq, Dr Thomson argues that a conscious effort is required to avoid the defence relationship between both countries going stale.

Dr Thomson points out that in the mid-1980s, the Dibb Report on defence planning called for interoperability between the two forces to be maximised, which led to the countries co-operating on the Anzac-class frigate program, delivering eight ships to Australia and two to New Zealand.

"Thirty years later, defence relations remain cordial and multifaceted, but there's nothing like the Anzac project on the horizon to generate a sense of shared purpose," the report said.

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"At the same time, the interoperability of the two defence forces has eroded because of diminishing equipment commonality and divergent levels of sophistication. The situation won't be rectified any time soon: in 1986, Australia spent eight times more on defence than New Zealand, and today the ratio stands at 17 to 1."

Dr Thomson's report said affordable steps Australia and New Zealand could take to strengthen the alliance is to invite Kiwi forces to participate more frequently in combined exercises with the US and better co-ordinate humanitarian response to disasters in south-east Asia and the South Pacific.

He also advocates a common approach to maritime surveillance, modelled on how the US and Canada work together on air defence.

The report suggests New Zealand could follow Australia's lead in replacing the ageing P-3 Orion maritime patrol aircraft with the P-8 Poseidon, or buy long-range drones to augment the system Australia is acquiring.

"Whether it's unauthorised people movements, fisheries protection in the South Pacific and Antarctica, or the entry of hostile forces into the region, both countries have a stake in knowing what's happening in their waters," the report said.

"By pooling physical assets and fusing data, they would stand to gain from co-operation. The resulting Australia-New Zealand Maritime Surveillance Command would be a 'static' capability that would be largely immune to the tensions inherent in politically contentious deployments."